Alignment of lens and image sensor

ABSTRACT

Embodiments related to the alignment of a lens with an image sensor in an optical device are disclosed. For example, one disclosed embodiment comprises an optical device including a printed circuit board, and an image sensor package mounted on the printed circuit board, wherein the image sensor package includes an image sensor. The optical system further comprises a lens holder including a lens, and one or more alignment features arranged on the lens holder. The one or more alignment features are configured to contact the image sensor package to mechanically align the lens holder with the image sensor package.

BACKGROUND

The manufacture of optical devices such as cameras may involve alignmentof optical elements that are mounted on a printed circuit board. Forexample, a lens may be aligned with an image sensor via mounting holesfor each of these components on the printed circuit board. However,printed circuit boards may be low-precision parts that are manufacturedwith loose tolerances. Therefore, in order to ensure proper alignment ofoptical elements mounted to a printed circuit board, an active alignmentprocess may be utilized such that a position of an optical element isadjusted while the optical system is “live” (i.e. while the image sensoris actively acquiring images).

However, such active alignment may be complex and require a high levelof skill, and therefore may lead to increased manufacturing costs.Furthermore, the alignment process may lead to deformation of thecircuit board upon which the elements are mounted, thereby negativelyaffecting the quality of the electronics.

SUMMARY

Accordingly, various embodiments are disclosed herein that relate toaligning optical elements mounted on a printed circuit board. Forexample, one disclosed embodiment comprises an optical system includinga printed circuit board, and an image sensor package mounted on theprinted circuit board, where the image sensor package includes an imagesensor. The embodiment further comprises a lens holder including a lens,and one or more alignment features arranged on the lens holder. The oneor more alignment features are configured to contact the image sensorpackage to mechanically align the lens holder with the image sensorpackage.

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Furthermore,the claimed subject matter is not limited to implementations that solveany or all disadvantages noted in any part of this disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an embodiment of a use scenario of adepth-sensing camera.

FIG. 2 is a schematic side view of an embodiment of an optical systemduring a lens holder installation and alignment process.

FIG. 3 is a schematic side view of an embodiment of an optical systemafter installation of the lens holder.

FIG. 4 is a flowchart illustrating an embodiment of a method foraligning optical components mounted to a printed circuit board.

DETAILED DESCRIPTION

As described above, aligning optical components that are mounted to aprinted circuit board may pose various challenges. For example, due tothe nature of the printed circuit board manufacturing process, it may bedifficult to form mounting holes for a lens and image sensor withdesired tolerances, even where a lens holder used to hold the lens andthe package for the image sensor are themselves precision parts.

Therefore, embodiments are disclosed herein that are related to mountingand aligning an image sensor and associated lens holder onto a printedcircuit board with sufficient precision that subsequent active alignmentsteps (e.g. manual adjustment of the lens while the image sensor islive) may be avoided. Before discussing these embodiments, an exampleoptical device is shown in FIG. 1 in the context of a user 102 playing avideo game in front of a computing system 104 having an embodiment of adepth-sensing camera 106. Images from the depth-sensing camera 106 maybe used by the computing device to detect the user's movements, and totransform the movements into graphical movements of an avatar of theplayer on the display 108. In this manner, the user 102 may control playof the video game through body movements alone, without the use of anyhand-held controller or other such device.

The depth-sensing camera 106 may include a plurality of optical elementswhich are aligned in order to detect the user's movements. Such opticalelements may include, but are not limited to, an image sensor mounted toa printed circuit board, and a lens or system of lenses to focus animage of the user onto the image sensor. FIG. 2 shows a schematicdepiction of an embodiment of such an optical system 200. The depictedoptical system 200 includes a printed circuit board (PCB) 202, and animage sensor package 204 mounted on the printed circuit board 202,wherein the image sensor package 204 comprises an image sensor 206.Image sensor 206 may be any suitable type of image sensor, including butnot limited to a complementary metal-oxide-semiconductor (CMOS) sensor.

The image sensor package 204 also includes various geometrical sensorpackage features. For example, the image sensor package 204 may includean image sensor package cover plate 208, and/or a datum corner 210. Suchgeometric features may be configured to have a precise geometricalignment relative to the image sensor 206. As such, the tolerances ofthe geometric features of the image sensor package 204 relative to theimage sensor 206 may be tighter than the tolerances of the geometricfeatures of printed circuit board that holds the image sensor 206.

Continuing with FIG. 2, a lens holder 212 is shown (e.g., a lens barrelholder), wherein the lens holder includes one or more lenses (notshown). The lens holder 212 also may be constructed with tightgeometrical tolerances, such that variation of the position of the lensis very small between lens holders.

In light of the tight geometric tolerances of the lens holder 212 andthe image sensor package 204 compared to the printed circuit board 202,a lens may be aligned with an image sensor in a more precise mannerwhere the lens holder 212 references the image sensor package 204directly, rather than referencing mounting holes in the printed circuitboard.

Accordingly, the lens holder 212 comprises alignment features that areconfigured to contact geometric features of the image sensor package 204to thereby mechanically align a lens within the lens holder 212 with theimage sensor 206 on the image sensor package 204. In this manner, directcontact between parts constructed with tight geometric tolerances isused to align the parts, rather than mutual contact with an interveningstructure (printed circuit board) that has looser tolerances.

Any suitable structures may be used as mounting features to facilitatethe alignment of the lens holder 212 to the image sensor package 204.For example, in the depicted embodiment, a recessed portion 214 of thelens holder 212 comprises one or more protrusions, such as firstprotrusion 216 and second protrusion 218, extending from an insidesurface of the recessed portion 214, and/or or from an interior side ofanother suitable portion of the lens holder 212. The protrusions areconfigured to snugly contact one or more selected geometric features onthe image sensor package to thereby align the lens holder (and thus anylenses in the lens holder) with the image sensor package an imagesensor. It will be understood that first protrusion 216 and secondprotrusion 218 are shown for the purpose of example, and that any othersuitable alignment feature may be used. For example, instead of aprotrusion, an alignment feature may comprise a notch configured toaccommodate a complementary geometric feature on the image sensorpackage.

As mentioned above, the alignment features (e.g. first protrusion 216and second protrusion 218 in the depicted embodiment) are configured tocontact the image sensor package 204 to mechanically align the lensholder 212 with the image sensor package 204. This is illustrated inFIG. 3. In this figure, it can be seen that the alignment features ofthe lens holder 212 are complementary to the geometrical sensor packagefeatures of the image sensor package 204 such that the first protrusion216 and second protrusion 218 fit snugly about the image sensor package204.

The alignment features may be configured to contact any suitablegeometric structures on the image sensor package. For example, in someembodiments, the alignment features may be configured to mechanicallyalign the lens holder 212 by contacting the image sensor package coverplate 208. In other examples, the alignment features may be configuredto mechanically align the lens holder 216 by contacting the sensorpackage datum corner 210, or both the datum corner and the image sensorpackage cover plate. Further, yet other embodiments may utilize othergeometric features of the sensor package cover to align a lens in a lensholder to an image sensor. Additionally, in other embodiments, a lensholder may comprise a recessed portion without protrusions (e.g. wherethe entirety of the recessed portion is sized to fit snugly over theimage sensor package).

The alignment features may be formed in any suitable manner. Forexample, depending upon how the lens holder 212 is constructed, thealignment features may be machined into the lens holder, cast or moldedas a part of the lens holder, or bonded to the lens holder as aseparately formed piece. It will be understood that these methods offorming the alignment features are described for the purpose of example,and are not intended to be limiting in any manner.

FIG. 4 shows an embodiment of a method 400 for aligning a lens holderwith an image sensor package mounted on a printed circuit board, wherethe lens holder includes one or more lenses and one or more alignmentfeatures, and the image sensor package includes an image sensor and oneor more geometrical sensor package features.

Method 400 comprises, at 402, placing the lens holder proximate to theimage sensor package, and then aligning the lens holder to the imagesensor package by contacting the one or more alignment features of thelens holders with the one or more geometrical sensor package features at406. For example, in some embodiments, this may comprise contacting oneor more alignment features with an image sensor package cover plate at408. In other embodiments, this may comprise contacting the one or morealignment features with a sensor package datum corner at 410.

At 412, the method 400 includes fixing the lens holder to one or more ofthe image sensor package and the printed circuit board. At 414, themethod 400 may further include placing the lens holder and printedcircuit board into a depth-sensing camera, or a webcam, or in any othersuitable optical device. Due to the tight tolerances of the geometricalfeatures of the lens holder and the image sensor package, it will beunderstood that the lens holder and printed circuit board may be placedinto the optical device without performing any additional lens-to-sensoralignment processes, such as active alignment processes, after fixingthe lens holder to the image sensor package and/or the printed circuitboard. It will be understood that the order of the individual processesof method 400 is presented for the purpose of example, and that theillustrated processes may be performed in any other suitable order. Asan example, the lens holder and/or printed circuit board may be placedinto a depth-sensing camera before alignment of the lens holder and theimage sensor package.

It will further be understood that the configurations and/or approachesfor aligning a lens with an image sensor in an optical device describedherein are exemplary in nature, and that these specific embodiments orexamples are not to be considered in a limiting sense, because numerousvariations are possible. The specific routines or methods describedherein may represent one or more of any number of processing strategies.As such, various acts illustrated may be performed in the sequenceillustrated, in other sequences, in parallel, or in some cases omitted.Likewise, the order of any of the above-described processes is notnecessarily required to achieve the features and/or results of theembodiments described herein, but is provided for ease of illustrationand description.

The subject matter of the present disclosure includes all novel andnonobvious combinations and subcombinations of the various processes,systems and configurations, and other features, functions, acts, and/orproperties disclosed herein, as well as any and all equivalents thereof.

The invention claimed is:
 1. An optical system, comprising: a printedcircuit board; an image sensor package mounted on the printed circuitboard, the image sensor package including an image sensor; and a lensholder mounted on the printed circuit board and in contact with theprinted circuit board, the lens holder including: a lens, and one ormore alignment features arranged on the lens holder, wherein the one ormore alignment features contact the image sensor package andmechanically align the lens holder with the image sensor package, theone or more alignment features comprising a recessed portion of the lensholder, the recessed portion having one or more protrusions arranged onan inside surface, the one or more protrusions extending towards theprinted circuit board from the inside surface of the recessed portion toa partial depth of the recessed portion, each protrusion comprising astraight inner edge extending in a direction parallel to a side of theimage sensor package and toward the printed circuit board to an end ofthe protrusion closest to the printed circuit board, and each protrusionof the one or more protrusions contacting each of one or more sides ofthe image sensor package along a direction extending toward the printedcircuit board while being spaced from the printed circuit board.
 2. Thesystem of claim 1, where the one or more alignment features are locatedwithin an inside of the lens holder.
 3. The system of claim 1, where theone or more alignment features are complementary to one or moregeometrical features of the image sensor package.
 4. The system of claim1, where the image sensor package includes an image sensor package coverplate, and where the one or more alignment features are configured tomechanically align the lens holder with the image sensor package coverplate.
 5. The system of claim 1, where the image sensor packagecomprises a sensor package datum corner, and where the one or morealignment features are configured to mechanically align the lens holderwith the image sensor package datum corner.
 6. The system of claim 1,where the optical system comprises a depth-sensing camera.
 7. The systemof claim 1, where the optical system comprises a webcam.
 8. A method foraligning a lens holder with an image sensor package mounted on a printedcircuit board, the lens holder mounted on the printed circuit board andin contact with the printed circuit board, the lens holder comprisingone or more lenses and one or more alignment features, the one or morealignment features comprising one or more protrusions located in arecessed portion of the lens holder, the one or more protrusionsextending along a direction towards the printed circuit board to apartial depth of the recessed portion, each protrusion comprising astraight inner edge extending in a direction parallel to a side of theimage sensor package to an end of the protrusion closest to the printedcircuit board and along the side of the image sensor package, and theimage sensor package comprising an image sensor, the method comprising:placing the lens holder proximate to the image sensor package; aligningthe lens holder to the image sensor package by contacting the straightinner edge of the one or more protrusions in the recessed portion of thelens holder with one or more sides of the image sensor package thatextend along a direction toward the printed circuit board such that thelens holder is in contact with the printed circuit board; and fixing thelens holder to the printed circuit board such that the one or moreprotrusions remain in contact with each of the one or more sides of theimage sensor package that extend along the direction toward the printedcircuit board and such that the one or more protrusions remained spacedfrom the printed circuit board.
 9. The method of claim 8, wherecontacting the one or more alignment features with the one or moregeometrical sensor package features comprises contacting the one or morealignment features to an image sensor package cover plate.
 10. Themethod of claim 8, where contacting the one or more alignment featureswith the one or more geometrical sensor package features comprisescontacting the one or more alignment features to a sensor package datumcorner.
 11. The method of claim 8, further comprising placing the lensholder and printed circuit board into a depth-sensing camera.
 12. Themethod of claim 11, further comprising placing the lens holder andprinted circuit board into the depth-sensing camera without performingany additional lens-to-image sensor alignment processes after the fixingof the lens holder to the one or more of the image sensor package andthe printed circuit board.
 13. The method of claim 11, wherein the lensholder and printed circuit board are placed into the depth-sensingcamera before fixing the lens holder to the one or more of the imagesensor package and the printed circuit board.
 14. The method of claim 8,further comprising placing the lens holder and printed circuit boardinto a webcam.
 15. A camera, comprising: a printed circuit board; animage sensor package mounted on a printed circuit board, the imagesensor package comprising an image sensor and an image sensor packagecover plate, the image sensor package comprising a sensor package datumcorner; and a lens holder mounted on the printed circuit board and incontact with the printed circuit board, the lens holder including: alens, and one or more alignment features located on an interior side ofthe lens holder, wherein the one or more alignment features arecomplementary to one or more of the image sensor package cover plate andthe sensor package datum corner, and wherein the one or more alignmentfeatures contact one or more of the image sensor package cover plate andthe sensor package datum corner and mechanically align the lens holderwith the image sensor package, the one or more alignment featuresfurther comprising a recessed portion of the lens holder, the recessedportion having one or more protrusions arranged on an inside surface,the one or more protrusions extending along a direction extending towardthe printed circuit board from the inside surface of the recessedportion to a partial depth of the recessed portion and contacting eachof one or more sides of the image sensor package along the directionextending toward the printed circuit board while being spaced from theprinted circuit board, each protrusion comprising a straight inner edgeextending in a direction parallel to a side of the image sensor packageto an end of the protrusion closest to the printed circuit board andalong the side of the image sensor package.
 16. The camera of claim 15,wherein the camera is a depth-sensing camera.
 17. The camera of claim15, wherein the camera is a webcam.